Continuous control system for a mining or tunnelling machine

ABSTRACT

A continuous control system for a mining or tunnelling machine having a boom (12) with a motor driven cutting head (14) at one of its ends and a rotatable turret (20) at the other end, the control system comprising angular encoders (40, 44) for continuously measuring the angles of the boom (12) and of the turret (20) and a linear encoder (55) for continuously measuring the linear position of the cutting head (14), and further having pressure transducers (P 1 , P 2 , P 3 , P 4 ) for continuously measuring the pressures of the various hydraulic cylinders or drives (41, 43) used to operate the boom (12) and the turret (20). It may also have a power transducer (57) for continuously measuring the power input to the motor (18) driving the cutting head (14) to control the RPM of the latter. The signals from the above various measurements are continuously processed by a computer (46) in accordance with a predetermined computer program and a controller (47) is provided which is responsive to the computer (46) and which continuously controls the various parameters so as to cut a preselected profile at a predetermined depth of cut and rate of advance.

TECHNICAL FIELD

This invention relates to a continuous control system for a mining ortunnelling machine having a tiltable boom with a rotatably drivencutting head at one end of said boom, projecting toward the face to becut, and at its other end the boom being connected to a rotatable turretwhich also enables said boom to rotate. Such machines are generallyknown as heading machines or roadheaders or boom mining or tunnellingmachines.

BACKGROUND OF THE INVENTION

Various control systems have in the past been proposed for mining ortunnelling machines. One such system, for example, is disclosed inInternational Patent Application (PCT) WO 91/18184 published Nov. 28,1991. The machine disclosed therein is of a particular type with a largerotatable cutting wheel which is moved laterally as it rotates, therebycutting a face having a height that essentially corresponds to thediameter of the cutting wheel. The control system of such a machinecannot be readily adapted to boom type mining or tunnelling machineswherein the boom is both tiltable and rotatable to achieve a desiredprofile of the cut, where "profile" means any path that the boom isdirected to take, limited only by the mechanical constraints or themachine.

Other known systems provide for the cutting of a predetermined profile,but without a continuous control of the operation which enablesappropriate corrections to be made as the face is being cut and whilethe machine is operating. Such known control systems are rudimentary inthat control of individual movements (e.g. via control of individualhydraulic circuits or electric motors) is done in an essentiallyopen-loop fashion, i.e. although there is some monitoring of theposition of sump, boom and turret-rotation, the system is not able toreact to that information other than in a discontinuous fashion. Forprofile cutting, a cam or a particular, simple cam algorithm for a givenset of profile dimensions may be used to produce discrete, separatemovements of boom and turret at certain distance intervals of movementof one or the other of boom-pivot or turret-rotation; this produces aprofile accurate to within one or two degrees of movement of boom and/orturret (of the order of 3-5 cm. at best in terms of the profile itself).The lack of continuous control in known machines results in, not onlyinaccuracy of position and change of position (movement) in sump,boom-pivot and turret-rotate, but consequent with that inaccuracy, agreat potential for variation in the rate of movement through the rockand thus a similar great potential for variation in forces experiencedby the cutting head and tools. In hard rock cutting, for example, thislack of continuous and accurate control of position, movement and forceresults in, at best, an inaccurate profile and a much shortened toollife and, at worst, an almost total inability to penetrate and cut therock. In very fractured ground, such uncontrolled cutting can alsoresult in undesired blocks of rock being torn or pulled from theperimeter of an excavated opening, thus exacerbating ground controlproblems. A further disadvantage of the previous systems is that for anychange in profile dimensions, an entirely new set of corresponding boomangle and turret angle values would have to be generated externally andthen programmed into the machine computing system.

Thus, no satisfactory continuous control system appears to exist for aboom type machine such as mentioned above, wherein the boom is tiltableand rotatable and wherein the cutting head is also rotated using aseparate motor or hydraulic drive for that purpose.

SUMMARY OF THE INVENTION

An object of the present invention is, therefore, to provide a novelcontinuous control system for a mining or tunnelling machine of the typereferred to above, namely having a tiltable and rotatable boom and acutting head rotated by a separate electric motor or hydraulic drive.

Another object of the invention is to optimize the control system sothat proper corrections are continuously made to cut a preselectedprofile at a predetermined depth of cut and rate of advance.

Other objects and advantages of the invention will become apparent fromthe following description thereof.

Thus, in essence, the present invention provides a continuous controlsystem for a mining or tunnelling machine having a boom with a cuttinghead which projects towards the face to be cut mounted at one end of theboom, and having means for rotating said cutting head at one or more RPMvalues, said boom, at its other end, being tiltably connected to arotatable turret for rotation therewith, and means being provided forrotating said turret, the boom being tilted by means of at least onehydraulic cylinder with a piston slidable therein, said at least onehydraulic cylinder being connected at one end to the turret and at theother end to the boom so as to tilt the same when said piston isadvanced out of or retracted into the hydraulic cylinder, said controlsystem comprising:

a first angular encoder for continuously measuring the tilt angle of theboom;

a second angular encoder for continuously measuring the angle ofrotation of the turret;

a linear encoder for continuously measuring linear position of thecutting head;

a computer responsive to output signals from said encoders configured tocontinuously process said signals according to a predetermined computerprogram; and

a controller responsive to said computer, which controls proportionalvalve means which, in turn, control flow of hydraulic fluid into said atleast one hydraulic. cylinder, and further controls the speed ofrotation of the turret as well as the linear advance of the cuttinghead, thereby continuously controlling the boom angular position, theangular position of the turret and the linear position of the cuttinghead, so as to cut a preselected profile at a predetermined depth of cutand rate of advance.

In accordance with a preferred embodiment of the present invention,there is provided a continuous control system for a mining or tunnellingmachine having a boom with an electric motor driven cutting head at oneof its ends, said cutting head projecting toward the face to be cut andsaid boom, at its other end, being tiltably connected to a rotatableturret which is adapted to be rotated by means of hydraulic drives,thereby also rotating the boom as the turret is rotated, said boom beingtiltable by means of at least one hydraulic cylinder with a pistonslidable therein, said hydraulic cylinder being connected, at one end,to the turret and, at the other end, to the boom so as to tilt th e same when the piston is projected out of or retracted into the hydrauliccylinder , the control system comprising:

a first angular encoder for continuously measuring the tilt angle of theboom;

a second angular encoder for continuously measuring the angle ofrotation of the turret;

a linear encoder for continuously measuring the linear position of thecutting head;

means for measuring pressure of the hydraulic drives rotating theturret;

means for measuring pressure at each end of said at least one hydrauliccylinder used for tilting the boom;

means for selecting RPM of the electric motor driven cutting head;

a computer responsive to output signals from said encoders and saidpressure measuring means, configured to continuously process saidsignals according to a predetermined computer program;

a controller responsive to said computer, which controls proportionalvalve means which, in turn, control flow of hydraulic fluid into said atleast one hydraulic cylinder and into the turret hydraulic drives, andfurther controls linear advance of the cutting head, thereby controllingthe boom angular position, the angular position of the turret and thelinear position of the cutting head, said controls being continuouslyadapted to operate in accordance with the computer program so as to cuta preselected profile at a predetermined depth of cut and rate ofadvance.

The RPM of the cutting head may be pre-set at a constant rate or avariable speed drive may be provided to control said RPM at a variablerate. It should be noted that when the computer is used to control thevariable speed drive, the speed, at any time, is set by the computerprogram acting on chosen and/or measured parameters, such as cuttinghead motor input power or boom vibration amplitude and/or frequency.

The continuous control system of the present invention may be used onmachines wherein the rotatable turret is rotated about a horizontal axisor a vertical axis. In machines with turrets having a horizontal axis ofrotation, these are followed by a non-rotatable housing wherein thehydraulic drives or motors for rotating the turret are mounted. Thishousing can be moved forward or back by means of sumping cylinders andmeans may be provided to measure hydraulic pressure therein, which maythus be used to control the linear position of the cutting head. Themovement of the housing extends for a particular distance (e.g. onemeter) while the machine is held stationary, for example by means ofsuitable stabilizing means, such as stakers, grippers, stells orstabilizers. Some machines have a telescopically extendable boom whichwould also provide a means of controlling the linear position of thecutting head. Such linear position can also be continuously measured bymeans of a suitable linear encoder the signals whereof are then sent tothe computer and included in the computer program as one of thefunctions to be controlled.

Angular and linear encoders for continuously measuring the angular orlinear positions are well known in the art. These are usuallyopto-electronic devices which provide readings every fraction of asecond, for example ten to twenty times per second, which herein iscalled a continuous operation. The signals from the encoders arecontinuously transmitted to the computer and are processed therebyaccording to a preselected computer program, which can include suitabletables or algorithms. The term "encoder" as used herein is, therefore, ageneral term including any device suitable for performing continuousangular or linear measurements and transmission of the resulting signalsto the computer.

The means for continuously measuring the various pressures consist ofpressure transducers which are also well known in the art. With regardto the electric motor for driving the cutting head, it may be controlledby a variable speed drive. However, the RPM of the cutting head couldalso be pre-set by the operator at one or more RPM values and maintainedessentially constant at that value. Of course, the RPM could also becontinuously controlled by the computer and the variable speed drive aspart of the overall program. The variable speed drive typically providesvariable power to run the motor driving the cutting head at a rate ofbetween about 3 and 10 RPM in hard or strong rocks and at what may bemuch higher rates in soft or weak rocks.

The controller normally comprises a plurality of PID (ProportionalIntegral Derivative) controllers which continuously control the variousfunctions of the machine according to the instructions from the computerprogram. Preferably, the computer program is based on a mathematicalalgorithm which takes into account the various measured parameters andcalculates the required conditions to achieve a desired profile at thebest rate of advance while minimizing tool wear. This is normally donein a closed-loop operation.

The machines controlled in accordance with the present invention mayoperate with a hydraulic system which covers all rates of advance orwith a hydraulic system composed of two or more sub-systems, eachcovering a distinct range of advance rates. Thus, a typical set-up forcutting hard ground may consist of a hydraulic sub-system to accuratelyallow advance rates of 20-100 mm/min, and a second sub-system toaccurately allow advance rates of 100-1500 mm/min. The above mentionedadvance rates refer to the linear advance of the cutting head. Thecontrol system of the present invention will, in such circumstances,provide two separate sets of valve means in parallel for the flow ofhydraulic fluid into the boom cylinders and the turret hydraulic drives,one for the low rate of advance and one for the high rate of advance.This rate of boom advance can be represented by the following equation:

    RATE OF ADVANCE=DEPTH OF CUT/TOOL/REVOLUTION×NUMBER OF TOOLS/LINE×HEAD RPM

The number and type of tools per line and the number of tool lines onthe cutting head may vary depending on the machine and its desired use.The advantage of a hydraulic system with multiple sub-systems to coverdifferent rates of advance is that individual componentry, specificallyvalves, can be chosen to operate within flow and pressure ranges overwhich they will perform most accurately.

Thus, in its preferred embodiment, the novel control system is acontinuous, closed-loop, PID (Proportional, Integral Derivative)positional system whereby set-points ("should-be" values of boom-angle,turret-angle, and linear sump position) are continuously generated by acomputer typically in the order of ten to twenty times per second(actual frequency depends on chosen componentry and calculation time,but it is fixed and known at any time); actual positional information oneach of boom-angle, turret-angle and linear sump position is usuallyreceived at a frequency greater than set-point generation frequency, forexample, greater than twenty times per second. The difference betweenactual and "should-be" values is continuously reacted to by thecomputing capability and by specifically chosen hydraulic drives, valvesand pumps with the constant aim of driving that difference (error) tozero. This process is carried out for both individual movements of sump,turret-rotation and boom-pivot and for any combination of thesemovements. The result is a highly accurate, positional control system(typical error within about ±1 mm for linear sump and within about ±0.04deg. for each of boom angle and turret angle); also, because the rate atwhich set-points are generated is constant and is very rapid, the systembecomes a very accurate velocity control system for each movement orcombination of movements and, thereby, for the end of the boom to whichthe cutting head is attached; and consequent with the accurate velocityof traverse of the cutting head and a (pre-set) constant rotationalvelocity of said head or controlled variable velocity, the depth of cuttaken and the forces experienced by individual tools for that depth ofcut in a given rock type are finely controlled as well. And, in veryfractured ground, the disturbance to the perimeter of an opening isminimized. A further advantage of the new system is that, because agiven profile is described mathematically within the machine computingsystem, different profiles or opening dimensions or shapes (includingthose shapes asymmetrical to the machine centre-line) can be initiatedsimply and rapidly by changing a very small number of numerical valueswithin the computing system. The machine will then execute the newchosen path instructions automatically.

Another embodiment of the control system concerns the continuousmonitoring of cutting head motor input power, and the hydraulicpressures in each of the sump, turret-rotate, and boom-pivot systems.This information may be used in several ways:

a) the setting of discrete levels of power and pressure, the exceedanceof these levels for a chosen period of time automatically resulting in aspecified reduction in the rate of positional change of the end of theboom (i.e. a reduction in head traverse velocity); this reduction intraverse rate requires those systems which are governing the rate (sumpand/or turret-rotate and/or boom-pivot) to act in the same coordinatedfashion as described above; this is achieved by the same manner ofcomparing required positional values and actual positional values on acontinuous basis and constantly striving to drive the error to zero;

b) an extension to the above is the automatic resumption of the previoustraverse rate or the adoption of some other rate if power and/orpressure values remain below a certain level for a specific period oftime;

c) a further extension to the above is the continuous adjustment to therate of change of the cutting head (boom-end) position as power andpressure levels are maintained at specific levels or within specifiedranges.

A still further embodiment of the novel control system provides meansfor continuous monitoring of boom vibration amplitude and/or frequency,for instance through the use of accelerometers or velocity gauges placedon or adjacent to the boom, and automatic adjustment of boom traverserate and/or cutting head speed to maintain said vibration amplitudeand/or frequency within predetermined limits for the optimization oftool and machine component life.

A further extension to the control system of this invention providesmeans for continuous monitoring of tool temperature and/or tool forceand the automatic adjustment of either or both of boom traverse rate andhead speed to maintain the tool temperature and/or the tool force withinpredetermined limits for the optimization of tool life. The tooltemperature may, for instance, be monitored using thermocouples and thetool force using strain gauges.

The computer program may, for example, be based on the followingformulae which describe set-point generation for instances when thethree modes of operation of the machine occur concurrently and aconstant rate of change of position (i.e. constant velocity) of the boomis achieved. The instances cited are horizontal profiling with sump, andvertical profiling with sump (profiling involves both rotation of theturret and movement of the boom-pivot).

Basis

Accept that resultant boom velocity, V≈√VP² +VS²

where VP=Profiling velocity of boom

and VS=Sumping velocity of boom

Choose "V", and ratio desired between VP and VS (say ##EQU1## Set-PointGeneration 1) Horizontal Motion

Rotation Set-point given by: ##EQU2##

Elevation set-point given by:

    θ.sub.1 =sin.sup.-1 (y/L cos φ)

Sump set-point given by:

    A.sub.1 =A+VS/F

2) Vertical Motion

Rotation set-point given by: ##EQU3##

Elevation set-point given by:

    θ.sub.1 =sin.sup.-1 (x/L sin φ)

and Sump set-point given by

    A.sub.1 =A+VS/F

Where:

φ is present turret angle

φ₁ is turret angle set point

θ₁ is elevation angle set point

L is boom length

F is set point generation frequency

A is present sump position

A₁ is sump position set-point and,

for Horizontal Motion:

r is radius of great circle described by horizontal motion of cuttinghead

y is vertical distance between plane of great circle and boom pivotpoint

β_(o) is present angle within great circle of boom projection on tohorizontal plane

β_(c) is angular change within great circle per interval of time betweenset points and,

for Vertical Motion:

r is radius of great circle described by vertical motion of cutting head

x is horizontal distance between plane of great circle and boom pivotpoint

α_(o) is present angle within great circle by boom projection on tovertical plane

α_(c) is angular change within great circle per interval of time betweenset points.

On the basis of the above equations a suitable algorithm is provided toconfigure the computer for controlling the operation of the machine.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described withreference to the appended drawings, in which:

FIG. 1 is side-elevation view of a machine that may be controlled inaccordance with the present invention; and

FIG. 2 is a diagrammatic illustration of a preferred embodiment of thenovel control system for the machine of FIG. 1.

FIG. 3 is a side-elevation view of a machine according to the presentinvention having a turret rotatable about a vertical axis and othercontrols.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, it shows a machine 10 that may be provided with acontrol system of the present invention. This machine has a boom 12 atone end of which there is a cutting head 14 which is connected to theboom 12 through a cutting head gearbox 16. Cutting head 14 has cuttingtools 15 and is driven through the gearbox 16 by a motor 18 whichrotates the cutting head at a desired speed, for example between 3 and10 RPM for hard rock cutting. At the other end, said boom 12 isconnected to a rotatable turret 20 and can be tilted on the boom pivot22 by means of hydraulic cylinders 24 and 26 having pistons 28 and 30slidable therein. At one end these hydraulic cylinders are connected tothe turret 20 at points 32 and 34 and at the other end to the boom 12 atpoints 36 and 38, so as to tilt the boom 12 when the piston 28 eitherretracts or extends and piston 30 either extends or retracts into/fromtheir respective cylinders 24, 26. The tilt of the boom 12 typicallyvaries between 0 and 43° in such machines, but this is by no meanslimitative. The tilt angle of the boom 12 is continuously measured by anangular encoder 40 normally located at the boom pivot 22.

The rotatable turret 20 is followed by a non-rotatable housing 42 wherethe hydraulic drives for rotating the turret are located. An angularencoder 44 is provided to continuously measure the angle of rotation ofthe turret 20 and thus of the boom 12 on said turret. This angle ismeasured with reference to a predetermined line, usually the verticalaxis of the turret 20, and can vary from 0 to 360°. The computer andcontroller system 46, 47 is normally located at the back of the machine,however the operator interface 48 may be provided in the operatorstation 50. The machine moves on crawler tracks 52, however this type ofmachine can also be fixed laterally to the walls by side stakers 54 andto the roof by stakers 56 to provide stability during operation. In suchcircumstances, to advance the cutting head 14 during cutting of the rockface 58, the housing 42 is advanced by a predetermined distance, e.g. 1meter, as shown at 60, using sumping cylinders 62, 64 which may beachieved in two separate 0.5 m movements. The same distance is shown atthe front for head advance 66. Once this stroke or advance is achievedand the whole of the face area is cut, the stakers 54, 56 are released,the housing 42 is brought back to its starting position, the machine isadvanced on tracks 52 by the above predetermined distance, and thecutting process is begun again. The advance of the housing 42 and thusof the head 14 is also continuously monitored through a linear encoderand used by the computer to provide the necessary pressure on therockface 58 during the cutting operation. The machine is also providedwith a loading apron 68 with suitable gathering arms to load the rockwhich is being cut, which rock is then moved by means of conveyor 70 tothe back of the machine to be hauled away.

Referring to FIG. 2 wherein the same features are represented by thesame reference numbers as in FIG. 1, it shows boom 12 at one end ofwhich there is provided the cutting head 14 connected to the boom 12through a gear box 16. The cutting head 14 is provided with cuttingtools 15, such as picks or discs. Electric motor 18 is used to drivehead 14 at a predetermined speed which can be constant or variable.

At its other end, the boom 12 is tiltably connected to turret 20 which,in this case, is shown to be rotated in the direction of arrow 21. Itcan also be rotated in the opposite direction, if desired. The tiltingof the boom 12 is done about the boom-pivot 22 by means of hydrauliccylinders 24, 26 having pistons 28, 30 projecting therefrom. Thesecylinders are attached at one end to the rotatable turret 20 at points32, 34 and at the other end, through the pistons 28, 30, to the boom 12at points 36, 38.

Following the rotatable turret 20, there is provided a non-rotatablehousing 42 which is also sometimes called a non-rotatable part of theturret. Hydraulic drives 41, 43 are mounted in housing 42; they rotateturret 20 in the direction of arrow 21. This is done through gear boxes37, 39 and pinions 33, 35 engaging a single large slew ring adjacent topinions 33, 35 which rotates the turret. There are typically fourhydraulic drives used for this purpose. Turret 20, in turn, rotatesshaft 45 in the direction of arrow 49, the same as that of arrow 21.

Housing 42 is linearly movable in the direction of arrow 51 (or inopposite direction, if desired) while the machine is maintainedstationary. This is done by means of hydraulic cylinders 62, 64, whichare usually called sumping cylinders. In this manner the cutting head 14can also be moved in the same direction as shown by arrow 53.

The control of the excavation by the cutting head 14 is carried out asfollows:

a first angular encoder 40 is provided at the boom pivot 22 tocontinuously measure the tilt angle of the boom 12;

a second angular encoder 44 is provided at the end of shaft 45 tocontinuously measure the rotating angle of turret 20, which normallyrotates very slowly, for example, less than two complete rotations maybe required in excavating an entire face or opening to one depth of thecutting head;

a linear encoder 55 is provided to continuously measure the linearposition of the housing 42 and thus of the cutting head 14;

pressure transducers P₁ and P₂ are provided to continuously measure thepressure at each end of at least one hydraulic cylinder (e.g. 26) usedfor tilting the boom 12;

pressure transducers P₃ and P₄ are also provided to continuously measurethe pressure at each end of the hydraulic drives 41, 43 which are usedto rotate the turret 20;

pressure transducers P₅ and P₆ are used to continuously measure thepressure at each end of sumping cylinders 62, 64 which are used to movehousing 42 in the linear direction of arrow 51 and thus to move head 14in the same direction as represented by arrow 53; and

power transducer 57, shown adjacent to slip-ring assembly 59, is used tomeasure the power input to motor 18 which drives head 14.

The signals from all above measuring devices are transmitted to thecomputer 46 as indicated by broken lines in FIG. 2. A suitable programor algorithm is input into the computer by program device 63 and thedesired program for a given rock hardness or a given excavating speed orthe like may be selected by the operator through operator interface 48.The computer processes the various signals in accordance with thepreselected program on a continuous basis (e.g. ten to twenty time persecond) and sends, also on a continuous basis, instructions tocontroller 47, usually consisting of a plurality of PID controllerswhich control the various functions of the machine.

Thus, for the twin hydraulic system cited earlier, the controller willcontrol the hydraulic fluid input and output into valve 67 or 69depending on whether the advance is carried out at a low rate or a highrate and this will control the tilt angle θ of boom 12 at any giventime. The same control will be performed on hydraulic drives 41, 43 bycontrolling hydraulic fluid input and output into valves 71 or 73 againdepending on the rate of advance. This will control the rotational angleφ of the turret 20 at any given time. With these two controls, a desiredprofile can be cut with great precision.

The rate of sumping advance can be controlled by continuouslycontrolling the hydraulic fluid input and output into valve 72 which inturn will control the operation of cylinders 62 and 64 producing adesired advance rate of the housing 42 and thus of the cutting head 14.

Finally, the computer may also control the speed of rotation of thecutting head 14 through a variable speed drive 74. It should also benoted that this is an optional control feature since the speed ofrotation of the head 14 may also be pre-set to run at a desired constantRPM. As can be seen from FIG. 2, the control system of the presentinvention provides a continuous, closed-loop control of the machinewhich enables it to cut a preselected profile at a predetermined depthof cut and rate of advance.

Furthermore, to provide such automatic and continuous control, thevarious pressures, such as P₁, P₂, P₃, P₄, P₅ and P₆ may be programmedto operate within predetermined limits and if, for example, these limitsare exceeded in one or more instances, the computer will adjust someother function, e.g. reduce the rate of advance, in order that thepredetermined limits be reinstated. This enables the machine to operateat the best rate of advance while minimizing tool wear for any givenrock type or other situation.

It should be understood that the invention is not limited to a controlsystem for machines such as illustrated in FIG. 1. There are a number ofmachines which have a vertical axis rotatable turret to which the boomis tiltably connected. The novel control system can be readily adaptedto such machines as well as illustrated in FIG. 3 where turret 20Arotates about a vertical axis as shown by arrow 21A. Angular encoder 44is provided to continuously measure the angle of rotation of the turret20A and thus of the boom 12. As previously described with reference toFIG. 1 and FIG. 2 such measurements are monitored by the computer andcontroller system 46, 47 which is normally accessed through operatorinterface 48. Also, as indicated previously, boom 12 can be tilted onthe boom pivot 22 by means of the combination of hydraulic cylinder 26and piston 30 operated through hydraulic proportional valve 26. Angularencoder 40 is provided at the boom pivot 22 to continuously measure thetilt angle of the boom 12. In this embodiment, turret 20A is operated byelectric motor 77 in lieu of previously shown hydraulic drives 41, 43, Aspeed reducing gear box 78 connects the motor 77 to a slew ring drive 79to rotate turret 20A. Also as previously described with reference toFIG. 1 and FIG. 2, boom 12 is connected to cutting head 14 via gear box16 which is driven by electric motor 18 and power transducer 57 is usedto measure the power input to the motor 18. The boom vibration amplitudeand/or frequency can be measured by accelerometer 80. The cutting head14 is provided with cutting tools 15, such as picks or discs. Some ofthese cutting tools, for example those designated as 15A, may beprovided with thermocouples to monitor tool temperature and others, forexample those designated as 15B, may be provided with strain gauges tomonitor tool force. Also, there are machines with telescopic booms toprovide the sumping action and the novel control system can again bereadily used with such machines. Moreover, there are machines having twoor more booms instead of one and the control system of the presentinvention will equally be applicable to such machines with minor obviousadjustments. Furthermore, the electric motor driving the cutting headcould be replaced by a hydraulic drive. In such a case means would beprovided to measure the pressure of said drive and the resulting outputsignals would be processed by the computer as already described withreference to hydraulic drives driving the turret. Also, there may bemachines where the turret is driven by electric motors rather thanhydraulic drives; such machines can equally be controlled using thecontrol system of the present invention, whereby in lieu of measuringthe pressure of the hydraulic drives, means would be provided to measurethe power input to and RPM of the electric motors and the resultingsignals would be processed by the computer essentially as alreadydescribed with reference to the electric motor used for driving thecutting head.

Finally, referring to FIG. 2, it should be noted that not all machinesand all operations will necessarily require all the measurements andcontrols indicated therein. Some machines will not require two rates ofadvance and some may require only one pressure measurement at thevarious cylinders and valve means, instead of two illustrated in thepresent case. All will depend on the desired accuracy of operation andthe use to which the machine will be subjected. In other cases, one maywish to control some additional functions such as, for example, boomvibration amplitude and/or frequency or tool temperature and/or toolforce, or roof staker and side staker cylinder pressures. Thus, manymodifications obvious to those skilled in the art may be made withoutdeparting from the spirit of this invention and the scope of thefollowing claims. Obviously, also, any machine having the novelcontinuous control system is within the scope of the present invention.

We claim:
 1. A continuous control system for a mining or tunnellingmachine having a boom with a cutting head which projects toward the faceto be cut mounted at one end of the boom, and having means for rotatingsaid cutting head at one or more RPM values, said boom, at its otherend, being tiltably connected to a rotatable turret for rotationtherewith and means being provided for rotating said turret, the boombeing tilted by means of at least one hydraulic cylinder with a pistonslidable therein, said at least one hydraulic cylinder being connectedat one end to the turret and at the other end to the boom so as to tiltthe same when said piston is advanced out of or retracted into thehydraulic cylinder, said control system comprising:a first angularencoder for continuously measuring the tilt angle of the boom; a secondangular encoder for continuously measuring the angle of rotation of theturret; a linear encoder for continuously measuring linear position ofthe cutting head; a computer responsive to output signals from saidencoders configured to continuously process said signals according to apredetermined computer program; and a controller responsive to saidcomputer, which controls proportional valve means which, in turn,control flow of hydraulic fluid into said at least one hydrauliccylinder, and further controls the speed of rotation of the turret aswell as the linear advance of the cutting head, thereby continuouslycontrolling the boom angular position, the angular position of theturret and the linear position of the cutting head, so as to cut apreselected profile at a predetermined depth of cut and rate of advance.2. A control system according to claim 1, wherein the means for rotatingsaid cutting head comprise a hydraulic drive, and means are provided formeasuring pressure of said hydraulic drive, with the computer beingresponsive to output signals from said pressure measuring means tocontinuously process said signals according to a predetermined computerprogram.
 3. A control system according to claim 1, wherein a variablespeed drive is provided to control the RPM of the cutting head, with thecomputer continuously controlling said variable speed drive according toa predetermined computer program.
 4. A control system according to claim1, wherein the means for rotating said turret comprise electric motors,and means are provided to measure power input to and RPM of saidelectric motors, with the computer being responsive to output signalsfrom said power and RPM measuring means to continuously process saidsignals according to a predetermined computer program.
 5. A controlsystem according to claim 1, further comprising means for continuousmonitoring of tool temperature and/or tool force on the cutting head,with the computer being responsive to said monitoring so as tocontinuously adjust the tool temperature and/or tool force values, tomaintain the same within predetermined limits for the optimization oftool life.
 6. A control system according to claim 1, further comprisingmeans for continuously monitoring boom vibration amplitude and/orfrequency, with the computer being responsive to said monitoring so asto maintain the boom vibration amplitude and/or frequency values withinpredetermined limits, for the optimization of tool and machine componentlife.
 7. A control system according to claim 1, wherein the controllerconsists of a plurality of PID controllers.
 8. A control systemaccording to claim 1, wherein the computer is configured to provide aclosed-loop operation, continuously using signals from the variousmeasured parameters and continuously calculating the required conditionsto achieve a desired profile at the best rate of advance whileminimizing tool wear, and continuously transmitting appropriate commandsto the controller.
 9. A continuous control system for a mining ortunnelling machine having a boom with an electric motor driven cuttinghead at one of its ends, said head projecting toward the face to be cutand said boom, at its other end, being tiltably connected to a rotatableturret which is adapted to be rotated by means of hydraulic drives,thereby also rotating the boom as the turret is rotated, said boom beingtiltable by means of at least one hydraulic cylinder with a pistonslidable therein, said at least one hydraulic cylinder being connectedat one end to the turret and at the other end to the boom so as to tiltthe same when said piston is projected out of or retracted into thehydraulic cylinder, said control system comprising:a first angularencoder for continuously measuring the tilt angle of the boom; a secondangular encoder for continuously measuring the angle of rotation of theturret; a linear encoder for continuously measuring linear position ofthe cutting head; means for measuring pressure of the hydraulic drivesrotating the turret; means for measuring pressure at each end of said atleast one hydraulic cylinder used for tilting the boom; and means forselecting RPM of the electric motor driven cutting head; a computerresponsive to output signals from said encoders and said pressuremeasuring means, configured to continuously process said signalsaccording to a predetermined computer program; and a controllerresponsive to said computer, which controls proportional valve meanswhich, in turn, control flow of hydraulic fluid into said at least onehydraulic cylinder and into the turret hydraulic drives, and furthercontrols linear advance of the cutting head, thereby continuouslycontrolling the boom angular position, the angular position of theturret and the linear position of the cutting head, so as to cut apreselected profile at a predetermined depth of cut and rate of advance.10. A control system according to claim 9, wherein the machine operatesin a plurality of ranges of rate of advance and wherein the proportionalvalve means which control the flow of hydraulic fluid into the boomcylinders and into the turret hydraulic drives, consist of several setsof valves in parallel, each set being used for a different range of rateof advance of the machine.
 11. A mining or tunnelling machine having aboom with a cutting head which projects toward the face to be cutmounted at one end of the boom, and having means for rotating saidcutting head at one or more RPM values, said boom, at its other end,being tiltably connected to a rotatable turret for rotation therewithand means being provided for rotating said turret, the boom being tiltedby means of at least one hydraulic cylinder with a piston slidabletherein, said at least one hydraulic cylinder being connected at one endto the turret and at the other end to the boom so as to tilt the samewhen said piston is advanced out of or retracted into the hydrauliccylinder, said machine having a continuous control system comprising:afirst angular encoder for continuously measuring the tilt angle of theboom; a second angular encoder for continuously measuring the angle ofrotation of the turret; a linear encoder for continuously measuringlinear position of the cutting head; a computer responsive to outputsignals from said encoders configured to continuously process saidsignals according to a predetermined computer program; and a controllerresponsive to said computer, which controls proportional valve meanswhich, in turn, control flow of hydraulic fluid into said at least onehydraulic cylinder, and further controls the speed of rotation of theturret as well as the linear advance of the cutting head, therebycontinuously controlling the boom angular position, the angular positionof the turret and the linear position of the cutting head, so as to cuta preselected profile at a predetermined depth of cut and rate ofadvance.
 12. A mining or tunnelling machine according to claim 11,having a turret rotatable about a horizontal axis followed by anon-rotatable housing where means are mounted for rotating said turret.13. A mining or tunnelling machine according to claim 12, in which thelinear position of the cutting head is continuously adjusted by means ofsumping cylinders which move the non-rotatable housing in a lineardirection, which position is measured by the linear encoder, saidadjustment being done through valve means controlled by the controller.14. A mining or tunnelling machine according to claim 11, which isfurther provided with stabilizing means to enhance the stability of themachine during the cutting operation.
 15. A mining or tunnelling machineaccording to claim 11, having a turret rotatable about a vertical axis.16. A mining or tunnelling machine having a boom with an electric motordriven cutting head at one of its ends, said head projecting toward theface to be cut and said boom, at its other end, being tiltably connectedto a rotatable turret which is adapted to be rotated by means ofhydraulic drives, thereby also rotating the boom as the turret isrotated, said boom being tiltable by means of at least one hydrauliccylinder with a piston slidable therein, said at least one hydrauliccylinder being connected at one end to the turret and at the other endto the boom so as to tilt the same when said piston is projected out ofor retracted into the hydraulic cylinder, said machine having acontinuous control system comprising:a first angular encoder forcontinuously measuring the tilt angle of the boom; a second angularencoder for continuously measuring the angle of rotation of the turret;a linear encoder for continuously measuring linear position of thecutting head; means for measuring pressure of the hydraulic drivesrotating the turret; means for measuring pressure at each end of said atleast one hydraulic cylinder used for tilting the boom; and means forselecting RPM of the electric motor driven cutting head; a computerresponsive to output signals from said encoders and said pressuremeasuring means, configured to continuously process said signalsaccording to a predetermined computer program; and a controllerresponsive to said computer, which controls proportional valve meanswhich, in turn, control flow of hydraulic fluid into said at least onehydraulic cylinder and into the turret hydraulic drives, and furthercontrols linear advance of the cutting head, thereby continuouslycontrolling the boom angular position, the angular position of theturret and the linear position of the cutting head, so as to cut apreselected profile at a predetermined depth of cut and rate of advance.17. A mining or tunnelling machine according to claim 16, having aturret rotatable about a horizontal axis followed by a non-rotatablehousing where means are mounted for rotating said turret.
 18. A miningor tunnelling machine according to claim 17, in which the linearposition of the cutting head is continuously adjusted by means ofsumping cylinders which move the non-rotatable housing in a lineardirection, which position is measured by the linear encoder, saidadjustment being done through valve means controlled by the controller.19. A mining or tunnelling machine according to claim 16, which isfurther provided with stabilizing means to enhance the stability of themachine during the cutting operation.
 20. A mining or tunnelling machineaccording to claim 16, having a turret rotatable about a vertical axis.